New Brown Dwarf Companions to Young Stars in Scorpius-Centaurus

Abstract

We present the discoveries of three faint companions to young stars in the Scorpius-Centaurus region, imaged with the NICI instrument on Gemini South. We have confirmed all three companions through common proper motion tests. Follow-up spectroscopy has confirmed two of them, HIP 65423 B and HIP 65517 B, to be brown dwarfs, while the third, HIP 72099 B, is more likely a very low-mass star just above the hydrogen burning limit. The detection of wide companions in the mass range of ~40--100 Mjup complements previous work in the same region, reporting detections of similarly wide companions with lower masses, in the range of ~10--30 Mjup. Such low masses near the deuterium burning limit have raised the question of whether those objects formed like planets or stars. The existence of intermediate objects as reported here could represent a bridge between lower-mass companions and stellar companions, but in any case demonstrate that mass alone may not provide a clear-cut distinction for the formation of low-mass companions to stars.

9 pages, 5 figures, accepted for publication in ApJL

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• Rotation Periods, Inclinations, and Obliquities of Cool Stars Hosting Directly Imaged Substellar Companions: Spin-Orbit Misalignments are Common
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• Sub-stellar Companions and Stellar Multiplicity in the Taurus Star-Forming Region
• A Multiplicity Census of Intermediate-Mass Stars in Scorpius-Centaurus
• A Thermal Infrared Imaging Study of Very Low-Mass, Wide Separation Brown Dwarf Companions to Upper Scorpius Stars: Constraining Circumstellar Environments
• The shadow knows: using shadows to investigate the structure of the pretransitional disk of HD 100453
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